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The present invention relates to a hand position detecting
device for a timepiece and to an electronic timepiece provided
with the device.
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A hand position detecting device for detecting that
hands such as second hand, minute hand, and hour hand have
been once returned to their initial positions (e.g., the position
of just 12 o'clock) is known in a timepiece having a radio
correction function of correcting the time by receiving standard
radio waves including time information. In a known structure
of this handposition detecting device, a light-emitting device,
a light-receiving device, and a reflective surface are so
arranged that hand wheels whose rotational positions are to
be detected are interposed among them. When each hand wheel
reaches a given position, light from the light-emitting device
is made to hit the reflective surface via the aperture in
the hand wheel, and reflected light reflected by the reflective
surface is detected by the light-receiving device via the
aperture in the hand wheel (for example, JP-A-2000-35489
and Japanese Patent No. 2941576 (patent publication gazette)).
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In these hand position detecting devices, however, the
reflective surface that gives information about the initial
position is present at one location and so where all of the
hour wheel, minute wheel, and second wheel are rotationally
driven by one motor, it is necessary to rotationally drive
the hands by amounts corresponding to 12 hours at a maximum to
set the hands to their initial positions. Furthermore, while
they are being rotationally driven, it is necessary to keep
electrically feeding the light-emitting and light-receiving
devices, as well as the motor and its rotational driver circuit.
Accordingly, the time taken to place them in their initial
positions is prolonged. In addition, where the driving source
is a battery, it is difficult to neglect the energy consumption.
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The present invention has been made in view of the
foregoing. It is an object to provide a hand position detecting
device capable of minimizing the rotation (the amount by which
the motor is rotationally driven or the number of driving
steps) of hand wheels necessary to ascertain their initial
positions and also to provide an electronic timepiece provided
with this device.
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To achieve the above-described object, the hand position
detecting device of the present invention in which, when first
hand wheel and a second hand wheel which is rotated in response
to rotation of the first hand wheel so as to make one rotation
as the first hand wheel makes an integral number of rotations,
have reached given positions, light from a light-emitting
device is made to hit regions formed in the second hand wheel
permitting light detection via an aperture formed in the first
hand wheel to pass incident light and the light made detectable
from the regions permitting light detection is detected by
a light-receiving device. The second hand wheel has the plural
regions permitting light detection, the regions being angularly
unequally spaced from each other such that the light-receiving
device receives the light made detectable when the second
hand wheel is also at plural intermediate rotational positions
other than the given positions.
-
In the hand position detecting device of the invention,
"the hour wheel has the plural regions permitting light detection
for light-receiving device to receive the light made detectable
when it is also at plural intermediate rotational positions
other than the given positions". Therefore, the rotational
angle of the second hand wheel or the time (the amount by
which the motor is rotationally driven or the number of driving
steps) required to detect the regions permitting light detection
can be small. Furthermore, in the hand position detecting
device of the invention, "the second hand wheel has the plural
regions permitting light detection, the regions being angularly
unequally spaced from each other". Therefore, after one region
permitting light detection is detected, the position of the
second hand wheel can be identified simply by detecting the
rotational angle of the second hand wheel necessary to detect
the next region permitting light detection (typically, a region
permitting light detection is detected twice). Consequently,
the second hand wheel can be set in a given position or another
given position having a given positional relation (angular
relation) to the former given position simply by rotating
the second hand wheel through an angle corresponding to the
given position based on the identified position. Hence, the
angle through which the hand wheel is rotated to place the
hand wheel into the given position or another given position
as described above can be reduced to a minimum. In addition,
the time required to place the hand wheel in position as described
above can be minimized. Also, the energy consumption can be
reduced to a minimum. Where the timepiece is a radio-controlled
timepiece or the like, the initial position typically
corresponds to the given position. Instead of the given position,
the initial position may also be the aforementioned another
given position having a certain positional relation to the
first-mentioned given position.
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In the hand position detecting device of the invention,
the regions of the second hand wheel permitting light detection
may be either reflective surfaces that reflect incident light
and produce reflected light or light transmissive regions
(apertures or regions made of a light transmissive material)
that transmit incident light and produce transmitted light.
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In the hand position detecting device of the invention,
where the regions of the second hand wheel permitting light
detection are reflective surfaces, the light made detectable
is reflected light. The light-receiving device is constructed
to detect the reflected light reflected by the reflective
surfaces via the aperture in the first hand wheel to pass
reflected light. In this case, incidence and reflection may
be made obliquely relative to the reflective surfaces or
substantially perpendicular to the reflective surfaces.
In the hand position detecting device of the invention, where
the incidence and reflection are performed obliquely relative
to the reflective surfaces, the device is so constructed that
when the first and second hand wheels have reached given
positions, light from the light-emitting device obliquely
hits the reflective surfaces on the second hand wheel via
the aperture in the first hand wheel to pass incident light.
Reflected light reflected obliquely by the reflective surfaces
is detected by the light-receiving device via the aperture
in the first hand wheel, the aperture being used for passage
of reflected light. On the other hand, in the latter case,
the aperture for passage of incident light and the aperture
for passage of reflected light consist of the same shared
aperture. When the first and second hand wheels reach the
given positions, light from the light-emitting device is made
to hit the reflective surfaces on the second hand wheel
substantially perpendicular via the shared aperture in the
first hand wheel, the shared aperture acting as the aperture
for passage of incident light. Reflected light reflected by
the reflected surfaces substantially perpendicular is
detected by the light-receiving device via the shared aperture
acting as the aperture in the first hand wheel for passage
of reflected light.
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In the hand position detecting device of the invention,
where the regions of the second hand wheel permitting light
detection are light transmissive regions, the light made
detectable is a transmitted hole passed through the light
transmissive regions of the second hand wheel. The
light-receiving device detects the transmitted hole from the
light transmissive regions.
-
In the hand position detecting device of the invention,
the angular interval between the regions of the second hand
wheel permitting detection is set to an integral multiple
of an incremental rotation angle through which the second
hand wheel rotates when the first hand wheel makes one rotation.
-
In the hand position detecting device of the invention,
the first hand wheel is typically a minute wheel and the second
hand wheel is an hour wheel. However, if desired, the first
hand wheel may be a second hand wheel, and the second hand
wheel may be a minute wheel. Furthermore, a set in which the
first hand wheel is a minute wheel and the second hand wheel
is an hour wheel and another set in which the first hand wheel
is a second hand wheel and the second hand wheel is a minute
wheel may be combined.
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In a typical hand position detecting device where the
first and second hand wheels are minute wheel and hour wheel,
respectively, the angular interval between the regions of
the hour wheel permitting detection (typically, reflective
surfaces) is typically an integral multiple of the incremental
angle, i.e., 30 degrees, through which the hour wheel acting
as the second hand wheel rotates when the minute wheel acting
as the first hand wheel makes one rotation. In this case,
the minute wheel can be set at positions shifted by amounts
that are precisely integral multiples of 1 hour, i.e., at
the same position as the given positions. Therefore, it is
assured that it is possible to detect whether any region of
the hour wheel permitting detection is in any given position
where incident light from the light-emitting device is received
and light made detectable is sent to the light-receiving device
simply by forming the aperture in the minute wheel to pass
incident light and the aperture to pass the light made detectable
(typically, reflected light) only at one location. That is,
in the hand position detecting device of the invention, the
hour wheel is provided with the regions permitting detection,
the regions being angularly spaced from each other by amounts
equal to integral multiples of 30 degrees. Therefore, events
permitting detection with the hour wheel such as reflection
are obtained at rotational positions shifted in time by integral
multiples of 1 hour. Meanwhile, the minute wheel returns to
the same position in a time shifted by an integral multiple
of 1 hour. Therefore, when the rotational position of the
hour wheel is detected, the minute wheel is automatically
placed in position. Also, where the second wheel other than
the minute wheel is placed in position at the same time, the
same circumstance holds. Moreover, where an intermediate wheel
for mating together the hour and minute wheels and an
intermediate wheel for mating together the minute and second
wheels are placed in position simultaneously, the same
circumstance holds.
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In the hand position detecting device of the invention,
the hour wheel typically has four regions (typically, reflective
surfaces) permitting detection, the regions being spaced from
each other in the direction of rotation. The four regions
include a reference position where incident light from the
light-emitting device is supplied as light made detectable
(typically, reflected light) to the light-receiving device
when the hour wheel is in a given position. In this case,
the angular intervals between any adjacent regions,one of
the four regions permitting detection are typically 30 degrees,
60 degrees, 120 degrees, and 150 degrees.
-
In this case, the position of the hand wheel can be
identified simply by rotating the hour wheel about 180 degrees
(corresponding to 6 hours) at a maximum. The hand wheel can
be quickly placed in position. Also, the energy consumption
can be suppressed to a minimum.
-
The angular intervals between any adjacent regions of
the four regions (e.g., reflective surfaces) permitting
detection may be 30 degrees, 60 degrees, 90 degrees, and 180
degrees, instead of 30 degrees, 60 degrees, 120 degrees, and
150 degrees.
-
In the hand position detecting device of the invention,
where it is desired to reduce the number of the regions formed
on the hour wheel and permitting detection (e.g., reflective
surfaces), the hour wheel may have three regions (e.g.,
reflective surfaces) permitting detection, the three regions
being unequally spaced from each other in the direction of
rotation. The three regions include a reference position where
incident light from the light-emitting device is supplied
as light made detectable (e.g., reflected light) to the
light-receiving device when the hour wheel is in a given
position.
-
In the hand position detecting device of the invention,
where the first and second hand wheels are minute and hour
wheels, typically after the first region permitting detection
(such as a reflective surface) is detected by rotation of
the hour wheel, the light-emitting device and light-receiving
device are once stopped from being driven. Each time the hour
wheel rotates for one hour, the light-emitting and
light-receiving devices are driven during the time required
to detect whether the light from the light-emitting device
is received by the light-receiving device or not in the
rotational position. In this case, the light-emitting and
light-receiving devices are driven by electrically feeding
them practically during a time for which the hand wheels (hour
wheel and minute wheel) are required to be rotated to detect
the first region permitting detection. Therefore, the
consumption of energy required to drive the light-emitting
and light-receiving devices can be suppressed to a minimum.
Consequently, in a battery-driven case, the consumption of
the battery can be reduced to a minimum. That is, when the
reflective surface is detected second time, it is only necessary
to perform one detection as to whether reception of light
is present or not whenever a rotation corresponding to 1 hour
is made. Consequently, the light-emitting and light-receiving
devices are only required to be driven like sampling whenever
a rotation corresponding to 1 hour is made. Thus, the consumption
of energy required to drive the light-emitting and
light-receiving devices can be suppressed to a negligible
extent.
-
Where the hand position detecting device of the invention
is so configured that light from the light-emitting device
hits the reflective surfaces obliquely, is reflected obliquely
at the reflective surfaces, and enters the light-receiving
device, a V-shaped optical path is formed as a whole. If the
gap or the thickness between the mounting portions of the
circuit board where the light-emitting and light-receiving
devices are mounted and the reflective surfaces is relatively
small, the gap between the light-emitting and light-receiving
devices can be made relatively large. This reduces the danger
that the light-receiving device receives stray light. The
incidence angle and reflection angle at the reflective surfaces
are typically about 30 degrees, for example. However, as long
as the light-receiving device can receive the light with
sufficient strength, the angles may be about 45 degrees or
about 60 degrees in some cases, or even greater. As long as
the danger that a part of the light emitted from the
light-emitting portion is reflected at other than the given
(correct) reflective surfaces and erroneously enters the
light-receiving portion as stray light does not exist in practice,
the incidence angle and reflection angle may be set smaller.
For example, they may be about 15 degrees or less.
-
Where the hand position detecting device of the invention
is so configured that light from the light-emitting device
hits the reflective surfaces obliquely, is reflected obliquely
at the reflective surfaces, and enters the light-receiving
device, the aperture for passage of incident light and the
aperture for passage of reflected light are typically separated
by a partitional wall portion. In this case, there is little
danger that incident light passed through the aperture for
passage of incident light erroneously reaches the aperture
for passage of reflected light and so the danger that the
light-receiving device receives stray light can be suppressed
to a minimum. However, if desired, in the minute wheel or
the like whose rotational position is to be detected, the
aperture portion forming the aperture for passage of incident
light and the aperture portion forming the aperture for passage
of reflected light together form one elongated continuous
aperture. Where both minute and second wheels have the aperture
for passage of incident light and the aperture for passage
of reflected light and the minute wheel is located close to
the hour wheel having reflective surfaces, for example, even
if the aperture in the minute wheel for passage of incident
light and the aperture for passage of reflected light together
form one elongated continuous aperture, the second wheel located
remotely from the reflective surfaces typically has two
apertures separated from each other. The apertures may be
holes or windows made of a material transparent to the used
light.
-
Where the hand position detecting device of the invention
is so configured that light from the light-emitting device
is made to hit the reflective surfaces obliquely, is reflected
obliquely at the reflective surfaces, and enters the
light-receiving device, the direction in which the
light-emitting and light-receiving devices are spaced from
each other is set to a direction intersecting the radial
direction of the minute wheel and hour wheel whose rotational
positions should be detected, typically set to a direction
perpendicular to the radial direction, to avoid increase of
the size of the device. In this case, the space between the
aperture in a rotating part such as a gear to pass incident
light and the aperture to pass reflected light can be set
large for the diameter of the rotating part. Hence, the space
between the light-emitting device and light-receiving device
can be set relatively large. This can reduce the danger that
the light-receiving device receives stray light. That the
direction in which the light-emitting and light-receiving
devices are spaced from each other is set to intersect the
radial direction of the minute wheel and hour wheel whose
rotational positions should be detected (typically set to
a sense perpendicular to the radial direction) means that
the angle connecting the light-emitting and light-receiving
devices is oblique (typically, at right angles) relative to
the angle connecting the center axes of rotation of two gears
in a case where the rotational positions of the two gears
provided with the center axes of rotation parallel to each
other are detected at the same time, for example. It is not
necessary to arrange the light-emitting and light-receiving
devices between the two center axes of rotation. Consequently,
the size within the plane perpendicular to the axial direction
of the rotational position detecting device can be suppressed
to a minimum.
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A preferred form of the present invention is illustrated
in the accompanying drawings in which:
- Fig. 1 is a schematic functional block diagram of a
watch having a hand position setting device provided with
a hand position detecting device that is a preferred embodiment
according to the present invention;
- Figs. 2 show explanatory views schematically showing
the operation of the optical detection system of the watch
of Fig. 1 for detecting initial positions; A is an explanatory
view in cross section taken along line IIA-IIA of C; B is
an explanatory view in planar cross section showing the
arrangement of reflective surfaces on an hour wheel, as viewed
along IIB-IIB of A; and C is an explanatory view in cross
section (explanatory view in planar cross section) along line
IIC-IIC of A;
- Fig. 3 is a schematic circuit diagram showing one example
of the circuit configurations of light-emitting and
light-receiving portions of the hardware of Fig. 1;
- Fig. 4 is a flowchart illustrating the flow of processing
in a hand position setting device provided with a hand position
detecting device that is a preferred embodiment according
to the invention;
- Fig. 5 is an explanatory plan view showing a case in
which the hands of the watch of Fig. 1 are in their initial
positions;
- Figs. 6 show explanatory views of another preferred
embodiment according to the invention, schematically showing
the operation of the optical detection system in the watch
of Fig. 1 for detecting the initial positions; A and B are
explanatory views in cross section as viewed under the same
conditions as A and B, respectively, of Figs. 2; and
- Figs. 7 show explanatory views of a still other preferred
embodiment according to the invention, schematically showing
the operation of the optical detection system in the watch
of Fig. 1 for detecting the initial positions; A and B are
explanatory views in cross section as viewed under the same
conditions as A and B, respectively, of Figs. 2.
-
-
Some preferred modes of practice of the present invention
are described based on the preferred embodiments shown in
the accompanying drawings.
[Embodiment 1]
-
In a watch 1 that is a preferred embodiment according
to the present invention, as shown in Fig. 1, a signal P1
from a noscillator circuit 10 is frequency-divided by a frequency
divider circuit 11 into a pulse signal P2. Based on this pulse
signal, a control circuit 12 including a microprocessor 13
and a memory 14 sends a drive-and-control signal P3 to a motor
driver circuit 15. A motor 16 is rotated in accordance with
a driver signal P4 owing to the motor driver circuit 15. Thus,
a wheel train 17 mated to the output shaft of the motor 16
is rotated. The wheel train 17 includes intermediate wheel
trains and hand wheels such as a second wheel 23, a minute
wheel 24 acting as a first hand wheel, and an hour wheel 25
(Figs. 2) acting as a second hand wheel. A second hand 60,
a minute hand 61, and an hour hand 62 (Fig. 5) are mounted
to the second wheel 23, minute wheel 24, and hour wheel 25,
respectively. The memory 14 includes a ROM (read-only memory)
portion 55 loaded with a program 50 for detecting hand positions
as shown in the flowchart of Fig. 4 and a RAM portion 52 becoming
a working region. A hand wheel relative position data storage
portion 53 and a reflective surface interval counter 54
(described later) are formed in the RAM portion 52.
-
In the following description, it is assumed that the
output pulses P2 from the frequency divider circuit 11 are
pulses having a repetition frequency of 1 Hz during normal
motion of the hands, for simplicity of illustration. The gear
reduction ratio between the output shaft of the motor 16 and
the second wheel 23 is 1/30. Each time the motor 16 is made
to make a half rotation in a stepwise manner, the second hand
60 moves a distance corresponding to 1 second (makes a 1/60
rotation). The number of the second pulses P2 is counted by
the hand wheel relative position data storage portion 53
operating as a counter for the pulses P2. That is, the contents
of the hand wheel relative position data storage portion 53
correspond to the rotational positions, in seconds, of the
hand wheels 23, 24, and 25, i.e., hands 60, 61, and 62, in
a 1:1 relation.
-
The fact that the second wheel 23, minute wheel 24,
and hour wheel 25 acting as hand wheels are present at initial
positions Si1, Si2, and Si3 which are target positions (given
positions) is detected as shown in Figs. 2.
-
That is, as can be seen from A of Figs. 2, on a circuit
board 22, for example, a light-emitting portion 18 including
a light-emitting device 33 (Fig. 3) such as an LED and a
light-receiving portion 19 including a light-receiving device
31 (Fig. 3) such as a phototransistor are mounted at an interval
of D between these portions. Reflective surfaces 26, 27, 28,
and 29 acting as regions permitting light detection are formed
on the side of the hour wheel 25 that is opposite to the
light-emitting portion 18 and light-receiving portion 19.
The reflective surfaces are located in positions where incident
light Bi incident obliquely from the light-emitting portion
18 is reflected obliquely and supplied as reflected light
Br (as the light made detectable) to the light-receiving portion
19. The second wheel 23 and minute wheel 24 are respectively
provided with apertures 23i, 24i for passage of incident light
and apertures 23r, 24r for passage of reflected light at an
interval such that an incident light path Li permitting the
incident light Bi from the light-emitting portion 18 to just
hit the reflective surface 26, 27, 28, or 29 obliquely is
opened and, at the same time, a received light path Lr permitting
the reflected light Br to come out of the reflective surface
26, 27, 28, or 29 obliquely and just enter the light-receiving
portion 19 is opened when both hand wheels 23 and 24 are in
the initial positions Si1 and Si2 (the positions on the hour).
-
As can be seen from C of Figs. 2, the angle connecting
the light-emitting portion 18 and light-receiving portion
19 or the direction in which a plane defined by the incident
light path Li and reflected light path Lr extends is
perpendicular to the radial direction H as viewed in a plan
view (plane vertical to the center axis C of rotation) as
in C of Figs. 2. In other words, when the second wheel 23
and minute wheel 24 are in their respective initial positions
Si1 and Si2, the angle connecting the aperture 23i in the
second wheel 23 for passage of incident light and the aperture
23r for passage of reflected light and the angle connecting
the aperture 24i in the minute wheel 24 for passage of incident
light and the aperture 24r for passage of reflected light
are substantially perpendicular to the radial direction H.
The radial direction H referred to herein is the direction
connecting the midpoint of each line and the center axis C,
the line connecting the apertures 23i and 23r or connecting
the apertures 24i and 24r.
-
The thickness and size of the watch 1 are suppressed
to a minimum by arranging the light-emitting portion 18,
light-receiving portion 19, reflective surface 26, and so
on such that the incident light path Li and reflected light
path Lr form a V-shaped light path having a large aperture
angle and arranging the light-emitting portion 18 and
light-receiving portion 19 so as to be aligned perpendicular
to the radial direction H. This permits position detection
to be performed with high positional accuracy. The apertures
23i and 24i for passage of incident light are separated from
the apertures 23r and 24r for passage of reflected light via
wall portions 23w and 24w. This is useful in suppressing entry
of stray light into the light-receiving portion 19 after a
part of the light Bi coming out of the light-emitting portion
18 is reflected at other than the reflective surface (26,
27, 28, or 29) to thereby form the stray light. Also, it is
useful in enhancing the resolution relative to the rotational
angles of the hand wheels 23 and 24.
-
Of course, if desired, the aperture for passage of incident
light and the aperture for passage of reflected light may
be formed into one elongated continuous aperture. The direction
connecting the light-emitting portion 18 and light-receiving
portion 19 may intersect the radial direction H not
perpendicularly but at a smaller angle. In a case where a
relatively large size is tolerated, the direction may extend
along the radial direction.
-
In the initial positions Si1, Si2, and Si3 shown at
A and C of Figs. 2, the second hand 60, minute hand 61, and
hour hand 62 assume the positions of just 12 o'clock as shown
in Fig. 5.
-
Where the second wheel 23, minute wheel 24, and hour
wheel 25 are in their initial positions Si1, Si2, and Si3
in this way, the light Bi from the light-emitting portion
18 passes through the light paths Li and Lr and is just detected
as the reflected light Br by the light-receiving portion 19.
Therefore, it is found or detected that the second wheel 23,
minute wheel 24, and hour wheel 25 have reached the initial
positions Si1, Si2, and Si3. It follows that the second wheel
23, minute wheel 24, and hour wheel 25 are positionally set
at the initial positions Si1, Si2, and Si3.
-
A specific example of a circuit is described in further
detail by referring to the example shown in Fig. 3. The
light-emitting portion 18 consists of the light-emitting diode
33 and a current-limiting resistor 34, for example. The
light-receiving portion 19 consists of the phototransistor
31 and a resistor 32 for adjusting the light reception
sensitivity.
-
As shown at B of Figs. 2, the hour wheel 25 has the
fundamental reflective surface 26 at the position of just
12 o'clock. In addition, it has the reflective surfaces 27,
28, and 29 at positions which are shifted from the fundamental
reflective surface 26 by 30 degrees, 90 degrees, and 210 degrees,
respectively, clockwise C1. That is, the reflective surface
27 is at the position of 1 o'clock. The reflective surface
28 is at the position of 3 o'clock. The reflective surface
29 is at the position of 7 o'clock. Accordingly, the angular
interval A1 between the reflective surfaces 26 and 27 is 30
degrees. The angular interval A2 between the reflective surfaces
27 and 28 is 60 degrees. The angular interval A3 between the
reflective surfaces 28 and 29 is 120 degrees. The angular
interval A4 between the reflective surfaces 29 and 26 is 150
degrees. The intervals A1, A2, A3, and A4 are different in
size. At A of Figs. 2, the dial (not shown) and hands are
present under the figure.
-
Therefore, in this hand position detecting device 3,
the light from the light-emitting portion 18 is reflected
by the reflective surface 27, 28, or 29 and received by the
light-receiving portion 19 in cases where the hour wheel 25
is in the rotational position of just 1 o'clock (i.e., the
reflective surface 27 is located at the reflective position
K), the hour wheel is in the rotational position of just 3
o'clock (i.e., the reflective surface 28 is located at the
reflective position K), or the hour wheel is in the rotational
position of just 7 o'clock (i.e., the reflective surface 29
is located at the reflective position K), as well as in the
case where the hour wheel 25 is in the rotational position
of just 12 o'clock (i.e., the fundamental reflective surface
26 is at the reflective position K that is just located on
the incident light path Li). On the hour, the second wheel
23 and minute wheel 24 are located at the initial positions
Si1 and Si2, respectively, and so it is assured that the light
paths Li and Lr are opened.
-
Then, the flow of processing of an initial position
detection program 50 is described based on the flowchart of
Fig. 4, the program functioning to detect the initial positions
using the hand position setting device 2 provided with the
hand position detecting device 3 of a preferred embodiment
of the invention constructed as described so far. The processing
described in the flowchart is carried out by executing the
initial position detection program 50 by means of the CPU
13, the program being loaded in the memory 14.
-
When a radio-controlled correction is made, if an
instruction to the effect that the hands 60, 61, and 62 of
the watch 1 should be returned to the initial positions of
just 12 o'clock is issued, the hand position detecting device
3 itself is reset to its initial state. After this resetting
to the initial state, the watch 1 enters the forced reset
mode.
-
In the resetting of the hand position detecting device
3 itself to the initial state, the contents of the hand wheel
relative position data storage portion 53 are reset to zero,
for example. If desired, the contents in this reset state
may be saved to other storage region such that the state taken
during resetting can be reproduced.
-
Then, the light-emitting device 33 of the light-emitting
portion 18 and light-receiving device 31 of the light-receiving
portion 19 are started to be electrically fed and driven.
Emission of the beam Bi from the light-emitting device 33
of the light-emitting portion 18 begins (step S101 of Fig.
4).
-
Then, the watch 1 enters the forced reset mode. In this
forced reset mode, the repetition frequency of the pulses
P2 from the frequency divider circuit 11 of Fig. 1 is increased,
for example, by a factor of many tens or pulses having repetition
frequencies of more than many tens of Hz of the original output
from the frequency divider circuit 11 are adopted to drive
the motor. The second hand 60 is forcedly rotated at a high
speed of about 1 rotation/second or higher (step S102). When
rotation of the hands 60, 61, and 62 is started in this forced
reset mode, the contents of the hand wheel relative position
data storage portion 53 have been reset. Therefore, subsequent
positions of the hands 60, 61, and 62 (in other words, the
positions of the hand wheels 23, 24, and 25) correspond to
the counted values in the hand wheel relative position data
storage portion 53 in a 1:1 relation, it being noted that
the position assumed at the moment when a forced resetting
operation was started is taken as the initial position (origin).
-
In the forced reset mode, if one pulse P2 is produced
from the frequency divider circuit 11, the counted value of
the hand wheel relative position data storage portion 53 is
incremented by "1". Also, the motor 16 is rotated one step
via the driver circuit 15 (step S102 of Fig. 4). In response
to the stepwise rotation of the motor 16 in one step, the
second wheel 23 of the wheel train 17 rotates an amount
corresponding to 1 second. Also, the minute wheel 24 coupled
to the second wheel 23 via the wheel train and the hour wheel
25 coupled to the minute wheel 24 via the wheel train rotate
amounts corresponding to 1 second.
-
Under the state in which the hand wheels 23, 24, and
25 of the wheel train 17 have rotated amounts corresponding
to 1 second in this way, a check is performed as to whether
the light-receiving portion 19 has received the reflected
light Br which has been emitted from the light-emitting portion
18 and reflected by a reflective surface (step S103).
-
Where the light-receiving portion 19 does not receive
the light from the light-emitting portion 18, the program
goes back to step S102, where the motor 16 is again rotationally
driven one step forwardly. In the state taken after this rotation
through an angle corresponding to 1 second, a check is made
as to whether the light-receiving portion 19 has detected
the reflected light Br (step S103). This driving of the motor
16 for forward rotation (step S102) and the check performed
by the light-receiving portion 19 as to whether detection
of light is done or not (step S103) are repeatedly carried
out until the light-receiving portion 19 detects the reflected
light Br from any one of the reflective surfaces 26, 27, 28,
and 29.
-
When the second wheel 23 and minute wheel 24 reach
positions on the hour (i.e., the apertures 23i and 24i for
passage of incident light are aligned to thereby open the
incident light path Li and the apertures 23r and 24r for passage
of reflected light are aligned to thereby open the reflected
light path Lr) and, at the same time, the hour wheel 25 reaches
the rotational position of just 0 (12) o'clock, just 1 o'clock,
just 3 o'clock, or just 7 o'clock (i.e., any one of the reflective
surfaces 26, 27, 28, and 29 is located at the reflective position
K that should be the intersection of the incident light path
Li and reflected light path Lr), the light Bi coming out of
the light-emitting portion 18 passes through the incident
light path Li, reaches the reflective surface 26, 27, 28,
or 29, is reflected by the reflective surface 26, 27, 28,
or 29, and forms the reflected light Br that passes through
the reflected light path Lr. This reflected light reaches
the light-receiving portion 19, where the light is detected.
Therefore, the reflective surface interval counter 54 is reset
to zero. The program exits from the step S103 with YES. The
light-emitting device 18 and light-receiving device 19 are
once stopped from being driven (step S104).
-
This reflective surface interval counter 54 counts the
relative amount of rotation R of the motor 16 rotationally
driven after detection of any one of the reflective surfaces
26, 27, 28, and 29 at an accuracy of 1 second, the relative
amount of rotation R being expressed in terms of time or in
hours. Then, the motor 16 is driven forward at high speed
until the counted value of the reflective surface interval
counter 54 reaches 1 hour (e.g., 3, 600) (steps S105 and S106).
-
When rotational driving corresponding to 1 hour is
completed, the light-emitting device 33 of the light-emitting
portion 18 and the light-receiving device 31 of the
light-receiving portion 19 are again driven (step S107). A
check is made as to whether the light Br from the light-emitting
portion 18 is received by the light-receiving portion 19 (step
S108).
-
In particular, in steps S105 to S108, whenever the motor
16 is rotationally driven an amount corresponding to 1 hour,
the light-emitting device 33 and light-receiving device 31
are driven, and it is checked whether the light Br from the
light-emitting device 18 is received by the light-receiving
portion 19 (whether any one of the reflective surfaces 26,
27, 28, and 29 has reached the reflective position K that
is the intersection of the incident light path Li and reflected
light path Lr). During this interval, the reflective surface
interval counter 54 counts how many hours for which the motor
16 has been rotated.
-
After the first 1-hour rotational driving, when the
program first reaches the step S108, if the light-receiving
portion 19 detects the light Br, the program exits from the
step S108 with YES and stops the light-emitting device 33
and light-receiving device 31 from being driven (step S109).
Then, the program enters step S110, where the contents of
the reflective surface interval counter 54 are shown to be
1 hour. Since 1 hour has passed since the first detection,
the program exits from the step S110 with YES. The reflective
surfaces located at intervals of 1 hour are only the reflective
surface 26 located at the position of just 12 o'clock and
the reflective surface 27 located at the position of just
1 o'clock. Therefore, it can be seen that the reflective surface
27 produces the second reflection at this moment. Accordingly,
in step S113, the motor 16 is reversely driven an amount
corresponding to 1 hour to return the hour wheel 25 to the
position of just 12 o'clock (step S114). Thus, positional
resetting to the initial positions is completed.
-
On the other hand, after the first 1-hour rotational
driving, if the light Br is not detected by the light-receiving
portion 19 on reaching step S108, a check is performed as
to whether the time elapsed since the first detection has
reached 4 hours by referring to the contents of the reflective
surface interval counter 54 (step S115).
-
In this case, only one hour has passed and so the program
exits from the step S115 with NO and returns to the step S104,
where the light-receiving device 31 and light-emitting device
33 are once stopped from being driven.
-
Subsequently, the motor 16 is rotationally driven an
amount corresponding to 1 hour (steps S105 and S106). Then,
the light-receiving device 31 and light-emitting device 33
are driven, and a check is performed as to whether the light
is received by the light-receiving portion 19 (step S108).
-
Where the light-receiving portion 19 detects the light
Br, skip the step S108 with YES and stop the light-emitting
device 33 and light-receiving device 31 from being driven
(step S109) and enter the step S110, where it is found from
the contents of the reflective surface interval counter 54
that 2 hours have passed since the first detection. Therefore,
skip the step S110 with NO, enter step S111, and skip the
step S110 with YES. Since the reflective surfaces located
at intervals of 2 hours are only the reflective surface 27
at the position of just 1 o'clock and the reflective surface
28 at the position of just 3 o'clock, it is seen that the
reflective surface 28 located at the position of just 3 o'clock
produces the second reflection at this moment. Accordingly,
in step S114, the motor 16 is rearwardly driven an amount
corresponding to 3 hours, and the hour wheel 25 is returned
to the position of just 12 o'clock. Thus, positional resetting
to the initial positions is completed.
-
After it is rotationally driven an amount corresponding
to 2 hours after the first detection, if the light Br is not
detected by the light-receiving portion 19 on reaching the
step S108, a check is performed as to whether the amount of
rotational driving after the first detection has reached an
amount corresponding to 4 hours (step S115). The program exits
from the step S115 with NO and returns to the step S104, where
the light-receiving device 31 and light-emitting device 33
are once stopped from being driven.
-
Then, the motor 16 is further rotationally driven an
amount corresponding to 1 hour (steps S105 and S106). The
light-emitting device 33 and light-receiving device 31 are
driven, and a check is performed as to whether the light is
received by the light-receiving portion 19 (step S108).
-
Since it is unlikely that the light Br is detected by
the light-receiving portion 19 after 3 hours from the first
detection, skip the step S108 with NO and enter the step S115.
Furthermore, skip the step S115 with NO and again return to
the step S104, stop the light-receiving device 31 and
light-emitting device 33 once from being driven.
-
Thereafter, the motor 16 is further rotationally driven
an amount corresponding to 1 hour (steps S105 and S106). The
light-emitting device 33 and light-receiving device 31 are
driven, and a check is performed as to whether the light is
received by the light-receiving portion 19 (step S108). At
this instant, the contents of the reflective surface interval
counter 54 are 4 hours.
-
Where the light Br is detected by the light-receiving
portion 19, skip the step S108 with YES, the light-emitting
device 33 and light-receiving device 31 stop from being driven
(step S109) and enter the step S110, where 4 hours have passed
since the first detection. Therefore, skip the step S110 with
NO and then skip step S111 with NO. Since the reflective surfaces
located at intervals of 4 hours are only the reflective surface
28 located at the position of just 3 o'clock and the reflective
surface 29 located at the position of just 7 o'clock, it can
be seen that the reflective surface 29 in the position of
the just 7 o'clock produces the second reflection at this
instant. Accordingly, in step S112, the motor 16 is forwardly
driven an amount corresponding to 5 hours, and the hour wheel
25 is moved into the position of just 12 o'clock. Thus, positional
resetting to the initial positions is completed.
-
On the other hand, where the light Br is not detected
by the light-receiving portion 19, it follows that the
light-receiving portion 19 detects nothing even after the
motor is rotationally driven for 4 hours after the first
detection. Therefore, skip the step S115 with YES, and the
light-receiving device 31 and light-emitting device 33 stop
from being driven (step S116). Since the reflective surfaces
located at intervals corresponding to more than 4 hours are
only the reflective surface 29 at the position of just 7 o'clock
and the reflective surface 26 at the position of just 12 o'clock,
it can be seen that the motor is located at a position rotated
from the position of just 7 o'clock by an amount corresponding
to 4 hours, i.e., at the position of just 11 o'clock, at this
instant. Therefore, the motor 16 is further rotationally driven
an amount corresponding to 1 hour from the position of this
just 11 o'clock (step S117). The hour wheel 25 is moved into
the position of just 12 o'clock. Thus, positional resetting
to the initial positions is completed.
-
In the description provided so far, where the first
reflective surface is the reflective surface 26 at the just
12 o'clock, the motor is rotationally driven an average amount
corresponding to 2.5 hours to detect the reflective surface
26. Then, the motor is rotationally driven an amount
corresponding to 1 hour to detect the second reflective surface
27. Therefore, the motor is rotationally driven an average
amount corresponding to 3.5 hours as a whole.
-
On the other hand, where the first reflective surface
is the reflective surface 27 at just 1 o'clock, the motor
is rotationally driven an average amount corresponding to
0.5 hour to detect the reflective surface 27. Then, the motor
is rotationally driven an amount corresponding to 2 hours
to detect the second reflective surface 28. Therefore, the
motor is rotationally driven an average amount corresponding
to 2.5 hours as a whole.
-
Furthermore, where the first reflective surface is the
reflective surface 28 at just 3 o'clock, the motor is
rotationally driven an average amount corresponding to 1 hour
to detect the reflective surface 28. Then, the motor is
rotationally driven an amount corresponding to 4 hours to
detect the second reflective surface 29. It follows that the
motor is rotationally driven an average amount corresponding
to 5 hours as a whole.
-
In addition, where the first reflective surface is the
reflective surface 29 at just 7 o'clock, the motor is
rotationally driven an average amount corresponding to 2 hours
to detect the reflective surface 29. Then, the motor is
rotationally driven an amount corresponding to 4 hours to
detect that the second reflective surface 26 is not reached.
Consequently, the motor is rotationally driven an average
amount corresponding to 6 hours as a whole.
-
As described so far, this watch 1 is provided with the
plural reflective surfaces 26, 27, 28, and 29 which are spaced
from each other by different angular intervals A1, A2, A3,
and A4. Therefore, it is possible to determine where the initial
position is present simply by rotating the hour wheel 25 about
one half turn at maximum. Consequently, the initial position
can be determined quickly. Furthermore, in this watch 1, the
reflective surfaces are at positions on the hour. Therefore,
after the first reflective surface is detected, the initial
position can be determined simply by driving the light-emitting
device 33 and light-receiving device 31 for a short time whenever
the amount of rotation of the hour wheel 25 becomes an integral
multiple of an amount corresponding to 1 hour. In consequence,
the energy consumption can be suppressed to a minimum.
-
Instead of placing the reflective surface 29 at the
position of just 7 o'clock, for example, it may be placed
at the position of just 6 o'clock, for example. In this case,
the angular interval A3 is 90 degrees (corresponding to 3
hours). The angular interval A4 is 180 degrees (corresponding
to 6 hours). In this case, in order to detect or ascertain
the second reflective surface 29 after finding the first
reflective surface 28, rotation corresponding to 3 hours
suffices. That is, in step S115 of Fig. 4, a decision or evaluation
is made in 3 hours instead of 4 hours. The average time (amount
of rotation or the number of driving steps of the motor) required
to determine the position in a case where the second reflective
surface is the reflective surface at just 6 o'clock is 1 hour
+ 3 hours = 4 hours. The average time (amount of rotation
or the number of driving steps of the motor) taken to determine
the position in a case where the first reflective surface
is the reflective surface at just 6 o'clock is 1.5 hours +
3 hours = 4.5 hours. Note that where the first reflective
surface is the reflective surface at just 12 o'clock, the
average time taken to determine the position is 3 hours +
1 hour = 4 hours.
-
If the condition is limited to the condition where
reflection on the hour is detected, it is impossible to place
five or more reflective surfaces that are unequally spaced
from each other. Although the time taken to detect or ascertain
the position is prolonged, three reflective surfaces may be
placed at unequal angular intervals if desired. For example,
a combination of just 12 o'clock, just 1 o'clock, and just
3 o'clock (for simplicity of illustration, this is given by
(0, 1, 3) here) may be possible. Also, (0, 1, 4), (0, 1, 5),
(0, 1, 6), (0, 2, 5), (0, 2, 6), or (0, 3, 7) may be possible.
In the case where information about the time (amount of rotation
or the number of driving steps of the motor) taken until a
reflective surface is detected for the first time is not used
for position detection, if the order or combination of the
same angular intervals is varied, a substantially equivalent
result arises. Therefore, its description is omitted.
-
In the watch 1 shown in the embodiment described so
far, the rotational position is ascertained after 4 hours
from the first reception and detection of the light. Therefore,
the hands can be moved from the ascertained rotational positions
to arbitrary given positions. Accordingly, in the description
of the embodiment described so far, it has been assumed that
the reflective surface 26 is at the position of just 12 o'clock.
As long as the reflective surfaces 26, 27, 28, and 29 are
at positions on the hour (i.e., when the hour wheel is at
a position on the hour, the reflective surfaces 26, 27, 28,
and 29 supply the light Bi from the light-emitting device
18 as the reflected light Br to the light-receiving portion
19) , the reflective surface 26 does not need to be at a position
of just 12 o'clock. In some cases, it may be at a position
not on the hour. However, if the convenience of checking again
that the hour wheel 25 is set at the position of just 12 o'clock,
for example, is taken into account, there is preferably a
reflective surface at the position of just 12 o'clock.
-
Furthermore, in the flowchart of Fig. 4, information
about the amount of rotation of the driven motor in step S102
before the rotational position where the first reflection
is obtained is reached is not used. However, where the motor
is rotated an amount corresponding to more than 4 hours based
on the counted value of the hand wheel relative position data
storage portion 53 and a reflective surface is first detected
(in a case where the counted value exceeds 4 hours), for example,
arrival at the reflective surface 26 is ascertained
unconditionally. Where a reflective surface is first detected
after the motor is rotated an amount corresponding to more
than 2 hours, it is ascertained that the reflective surface
26 or 29 has been reached. Therefore, in the latter case,
if a second reflective surface is not detected after the motor
is further rotated an amount corresponding to 1 hour, it is
ascertained that the first reflective surface is the reflective
surface 29 (in a case where a second reflective surface is
detected after rotating the motor an amount corresponding
to 1 hour, the first reflective surface is the reflective
surface 27 in the same way as the flow of steps S108, S110,
and S113 of Fig. 4). In this way, the rotational position
of the hour wheel 25 may be ascertained with a smaller amount
of rotation for driving by making use of information about
the amount of rotation given to the motor in step S102 until
the rotational position where the first reflection is obtained
is reached. In this case, instead of gradually increasing
the interval expressed in terms of time or in hours using
the reflective surface 26 as a reference such as 1, 2, 4,
and 5, it is possible to reduce the amount of rotation necessary
to ascertain the position by alternating greater and smaller
intervals such as (1, 4, 2, 5) or (1, 5, 2, 4). However, the
average time for which the light-emitting device 33 and
light-receiving device 31 are driven is substantially dependent
on the amount of driving necessary to detect the first reflective
surface and, therefore, approximately the same in practice.
[Embodiment 2]
-
In the description of the embodiment provided so far,
the light-emitting device 33 and light-receiving device 31
are placed at an interval of D. The light Bi from the
light-emitting device 33 obliquely hits the reflective surface
26 or the like through the apertures 23i and 24i for passage
of incident light. The reflected light Br produced by oblique
reflection from the reflective surface 26 or the like is received
by the light-receiving device 31 via the apertures 23r and
24r for passage of reflected light. That is, an example of
oblique incidence and oblique reflection has been described.
Instead, the structure may be constructed as shown in Figs.
6.
-
In the hand position detecting device 3a of Figs. 6,
the light-emitting device 33 and light-receiving device 31
are placed close to each other such that they can be placed
substantially just opposite to the reflective surface 26 or
the like. The second wheel 23 has the shared aperture 23c
acting as the aperture for passage of incident light and as
the aperture for passage of reflected light. The minute wheel
24 similarly has the shared aperture 24c acting also as the
aperture for passage of incident light and as the aperture
for passage of reflected light.
-
Accordingly, in this hand position detecting device
3a, in a case where the second wheel 23, minute wheel 24,
and hour wheel 25 are in the initial positions Si1, Si2, Si3,
and so on, the light Bi from the light-emitting device 33
passes through the shared apertures 23c and 24c acting as
the aperture for passage of incident light and substantially
perpendicularly hits the reflective surfaces 26, 27, 28, 29,
etc. on the hour wheel 25. The reflected light Br produced
by substantially perpendicular reflection at the reflective
surfaces 26, 27, 28, 29, and so on passes through the shared
apertures 23c and 24c acting also as the aperture for passage
of reflected light and is received by the light-receiving
device 31 located close to the light-emitting device 33. Except
that the optical path from the light-emitting device 33 to
the light-receiving device 31 is different from that of the
hand position detecting device 3 as in Figs. 2, this hand
position detecting device 3a is configured substantially
similarly to the hand position detecting device 3 in other
respects.
[Embodiment 3]
-
Furthermore, in the description of the embodiment
provided so far, the regions of the hour wheel 25 permitting
light detection are the reflective surfaces on the hour wheel
25. The regions of the hour wheel 25 permitting light detection
may be light transmissive regions as shown in Figs. 7 instead
of reflective surfaces.
-
In the hand position detecting device 3b of Figs. 7,
the hour wheel 25 has apertures 26h, 27h, 28h, and 29h acting
as light transmissive regions in the same positions as the
reflective surfaces 26, 27, 28, and 29 instead of these
reflective surfaces 26, 27, 28, and 29. The device has a circuit
board 22d for detection. The light-receiving device 31 is
mounted on the circuit board 22d on the opposite side of the
wheel train 17 from the circuit board 22.
-
Accordingly, in this hand position detecting device
3b, in a case where the second wheel 23, minute wheel 24,
and hour wheel 25 are in the initial positions Si1, Si2, Si3,
etc., the light Bi from the light-emitting device 33 passes
through the apertures 23i and 24i in the second wheel 23 and
minute wheel 24 for passage of incident light and through
the apertures 26h, 27h, 28h, 29h, etc. in the hour wheel 25,
and is received by the light-receiving device 31 that is placed
just opposite to the light-emitting device 33 on the circuit
board 22d on the rear side of the hour wheel 25. This hand
position detecting device 3a differs from the hand position
detecting device 3a of Figs. 6 in that the regions of the
hour wheel 25 permitting light detection are formed by apertures
instead of reflective surfaces and that the light-receiving
device 31 is mounted, instead of the circuit board 22, on
the circuit board 22d on the opposite side of the wheel train
17. Except for these points, the hand position detecting device
3a is constructed substantially similarly to the hand position
detecting device 3a of Figs. 6 in other respects.
-
In the description of the embodiments provided so far,
all the hand wheels are rotated by one motor via wheel trains.
Where synchronization can be taken regarding rotational driving
of the motor when the structure is reset to its initial condition,
the wheel trains may be rotated by plural motors.
[Embodiment 4]
-
For example, in Figs. 6, an additional set of
light-emitting device 33a and light-receiving device 31a may
be provided at a different distance from the center of rotation
C on the circuit board 22 as indicated by the imaginary lines.
Also, another shared aperture 23ac capable of acting as the
aperture for passage of incident light and as the aperture
for passage of reflected light may be formed in the second
wheel 23 at a given angular position and at a radial position
where the incident light Bai and reflected light Bar between
the light-emitting device 33a and light-receiving device 31a
can be passed. Moreover, reflective surfaces 26a and so on
similar to the reflective surfaces 26, 27, 28, and 29 of the
hour wheel 25 may be formed on the minute wheel 24 at desired
angular intervals at given angular positions and at radial
positions where the surfaces can be placed just opposite to
the shared aperture 23ac.
-
In the hand position detecting device 3c constructed
in this way, the second wheel 23 acts as the first hand wheel
while the minute wheel 24 acts as the second hand wheel in
relation to the light-emitting device 33a and
light-receiving device 31a. Accordingly, in the
above-described embodiment, if the light-receiving device
31a detects that the second wheel 23 and minute wheel 24 have
arrived at given reference positions in relation to
the light-emitting device 33a and light-receiving device 31a
in the same way as in the case where the light-receiving device
31 detects that the minute wheel 24 acting as the first hand
wheel and the hour wheel 25 acting as the second hand wheel
have arrived at given angular positions in relation to
the light-emitting device 33 and light-receiving device 31,
then the positions of the second wheel 23 and minute wheel
24 can be detected in a short time from the amount of rotation
or the like occurring until the next given reference positions
for the second wheel 23 and minute wheel are detected by rotating
the second wheel 23 at high speed. Therefore, based on this
information about detection, the position on the hour, for
example, can be identified in a short time. Based on the position
on the hour, the position of the hour wheel 25 can be identified
at high speed in relation to the light-emitting device
33 and light-receiving device 31. In this case, the second
wheel 23 does not need to be associated with the set of
light-emitting device and light-receiving device 33, 31. For
example, the radius of the second wheel 23 may be smaller
than the radii of the other wheels 24 and 25. For instance,
the second wheel 23 or a wheel corresponding to it may not
be concentric with the minute wheel 24 or hour wheel 25.
-
The arrangement of such two sets of light-emitting and
light-receiving devices, their associated apertures for
passage of incident light, regions permitting light detection,
and so on is not limited to the embodiment of Figs. 6. Similar
arrangement may be adopted in the embodiments of Figs. 2 and
7. In this case, similar kinds may be combined out of oblique
reflection as in Figs. 2, vertical reflection as in Figs.
6, and transmission as in Figs. 7 regarding the two sets of
light-emitting and light-receiving devices. Also, two
dissimilar kinds may be combined.
-
The aforegoing description has been given by way of
example only and it will be appreciated by a person skilled in
the art that modifications can be made without departing from
the scope of the present invention.